Camera module and assembly method therefor

ABSTRACT

The present invention provides a method for assembling a camera module, including: preparing a first sub-lens assembly and a second sub-assembly, wherein the second sub-assembly includes a second sub-lens assembly and a photosensitive assembly fixed together; arranging the first sub-lens assembly on an optical axis of the second sub-lens assembly to form an optical system capable of imaging; adjusting a relative position of the first sub-lens assembly with respect to the second sub-lens assembly, so as to increase an actual measured resolution of imaging of the optical system, obtained by using the photosensitive element, to a first threshold, and decrease an actual measured image plane inclination obtained by using the photosensitive element to a second threshold; and connecting the first sub-lens assembly and the second sub-lens assembly. The present invention further provides a corresponding camera module

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Chineseapplication No. 201710814250.2, filed on Sep. 11, 2017 in the StateIntellectual Property Office of China, the disclosure of which isincorporated herein in its entirety by reference.

TECHNICAL FIELD

The present invention relates to the field of optical technologies, andspecifically to a camera module solution.

BACKGROUND

With the spread of mobile electronic devices, technologies related tocamera modules applied to mobile electronic devices to help users withimaging (for example, capturing a video or an image) have developedrapidly. In recent years, camera modules have been widely applied invarious fields such as health care, security protection, and industrialproduction.

To meet the increasingly extensive market demands, high resolution,small size, and large aperture are the irreversible trend of cameramodule development. The requirements of the market on the imagingquality of camera modules are becoming higher. Factors affecting theresolution of a camera module of a given optical design include thequality of an optical imaging lens assembly and the manufacturingdeviations introduced in the module packaging process.

Specifically, during the manufacturing process of the optical imaginglens assembly, factors affecting the resolution of the lens assemblyinclude assembly deviations of various parts, deviations in thickness oflens spacer elements, assembly deviations of the lenses, the change inthe refractive index of the lens material, and so on. Among them, theassembly deviations of various parts include the optical surfacethickness of each individual lens, the optical surface rise of the lens,the optical surface form, the radius of curvature, one-way and two-wayeccentricity of the lens, the optical surface inclination of the lens,and so on. The values of such deviations depend on the mold precisionand the molding precision control capability. The deviations inthickness of lens spacer elements depend on the machining precision ofthe elements. The assembly deviations of the lenses depend on thedimensional tolerances of the elements assembled and the assemblyprecision of the lens assembly. The deviations caused by the change inthe refractive index of the lens material depends on the stability ofthe material and the batch consistency.

The deviations of the elements affecting the resolution may manifest asan accumulative deterioration, and the accumulative deviation increasesas the number of lenses increases. In existing resolution solutions,dimensional tolerances of elements with high sensitivity are controlled,and lens turning is performed to increase the resolution. However,because a high-resolution, large-aperture lens assembly is sensitive andhas strict tolerance requirements, for example, 1 μm lens eccentricityleads to 9′ image plane inclination in some sensitive lens assemblies,the difficulty in lens machining and assembling increases. In addition,because the feedback period is long in the assembly process, thecapability of process index (CPK) of the lens assembly is low andfluctuates greatly, leading to a high failure rate. Moreover, asdescribed above, there are numerous factors affecting the resolution ofthe lens assembly, and such factors exist in various elements. Becausethe control of such factors is limited by the manufacturing precision,simply improving the precision of the elements only provides a limitedeffect, requires high costs, and cannot meet the increasingly highrequirements of the market on the imaging quality.

On the other hand, in the machining process of the camera module, theassembly process of each structural part (for example, photosensitivechip mounting, motor lens assembly locking) may lead to an inclinationof the photosensitive chip, and the resolution of the imaging module maybe unable to reach the given specification due to the accumulation ofmultiple inclinations, resulting in a low yield in the module factory.In recent years, in the module factory, when the imaging lens assemblyand the photosensitive module are assembled, an active alignment processis used to compensate for the inclination of the photosensitive chip.However, the compensation ability of such process is limited. Becausemultiple aberrations affecting the resolution are originated from theability of the optical system itself, the existing active alignmentprocess for the photosensitive module cannot compensate for theinsufficient resolution of the optical imaging lens assembly.

SUMMARY

The present invention is to provide a solution that can overcome atleast one of the defects of the prior art.

According to an aspect of the present invention, a method for assemblinga camera module is provided, comprising:

preparing a first sub-lens assembly and a second sub-assembly, whereinthe first sub-lens assembly comprises a first lens barrel and at leastone first lens, the second sub-assembly comprises a second sub-lensassembly and a photosensitive assembly fixed together, the secondsub-lens assembly comprises a second lens barrel and at least one secondlens, and the photosensitive assembly comprises a photosensitiveelement;

arranging the first sub-lens assembly on an optical axis of the secondsub-lens assembly to form an optical system capable of imaging andcomprising the at least one first lens and the at least one second lens;

adjusting a relative position of the first sub-lens assembly withrespect to the second sub-lens assembly, so as to increase an actualmeasured resolution of imaging of the optical system, obtained by usingthe photosensitive element, to a first threshold, and decrease an actualmeasured image plane inclination obtained by using the photosensitiveelement to a second threshold; and

connecting the first sub-lens assembly and the second sub-lens assembly,so that the relative position of the first sub-lens assembly and thesecond sub-lens assembly remain unchanged.

Wherein, in the step of adjusting the relative position of the firstsub-lens assembly with respect to the second sub-lens assembly, theadjustment of the relative position comprises:

increasing the actual measured resolution of imaging of the opticalsystem by moving the first sub-lens assembly with respect to the secondsub-lens assembly in an adjustment plane.

Wherein, in the step of adjusting the relative position of the firstsub-lens assembly with respect to the second sub-lens assembly, themovement in the adjustment plane comprises translation and/or rotationin the adjustment plane.

Wherein, in the step of adjusting the relative position of the firstsub-lens assembly with respect to the second sub-lens assembly, theadjustment of the relative position comprises: adjusting an angle of anaxis of the first sub-lens assembly with respect to an axis of thesecond sub-lens assembly.

Wherein, the steps to adjust the relative position of the first sub-lensassembly with respect to the second sub-lens assembly comprise thefollowing sub-steps:

moving the first sub-lens assembly with respect to the second sub-lensassembly in an adjustment plane, so as to increase actual measuredresolution of imaging of the optical system in a reference field,obtained by using the photosensitive element, to a correspondingthreshold; and

adjusting an angle of an axis of the first sub-lens assembly withrespect to an axis of the second sub-lens assembly, so as to increaseactual measured resolution of imaging of the optical system in a testfield, obtained by using the photosensitive element, to a correspondingthreshold, and decrease an actual measured image plane inclination inthe test field, obtained by using the photosensitive element, to thesecond threshold.

Wherein, the steps of adjusting the relative position of the firstsub-lens assembly with respect to the second sub-lens assembly furthercomprise:

moving the first sub-lens assembly with respect to the second sub-lensassembly in a direction z, so that an actual measured image plane ofimaging of the optical system, obtained by using the photosensitiveelement, matches a target surface, wherein the direction z is adirection along the optical axis.

Wherein, the adjustment plane is perpendicular to the direction z.

Wherein, a method for obtaining the actual measured image planeinclination comprises:

setting a plurality of targets corresponding to different test positionsin the test field; and

acquiring a resolution defocusing curve corresponding to each testposition based on an image output by the photosensitive assembly.

Wherein, the reaching of the second threshold is to make the positionoffset of the peak values of the resolution defocusing curvescorresponding to different test positions in the test field along theoptical axis direction reduce to the said second threshold.

Wherein, the reaching of the second threshold is to make the positionoffset of the peak values of the resolution defocusing curvescorresponding to different test positions in the test field along theoptical axis direction reduce to a range of +/−5 μm.

Wherein, a method for obtaining the actual measured resolution ofimaging of the optical system comprises:

setting a plurality of targets corresponding to different test positionsin the reference field and the test field; and

acquiring a resolution defocusing curve corresponding to each testposition based on an image output by the photosensitive assembly.

Wherein, in the sub-step of moving the first sub-lens assembly withrespect to the second sub-lens assembly in an adjustment plane, thereaching of the corresponding threshold is: increasing peaks ofresolution defocusing curves corresponding to different test positionsin the reference field to a corresponding threshold.

Wherein, in the sub-step of adjusting an angle of an axis of the firstsub-lens assembly with respect to an axis of the second sub-lensassembly, the reaching of the corresponding threshold comprises:increasing a smallest one of peaks of a plurality of resolutiondefocusing curves corresponding to different test positions in the testfield to a corresponding threshold.

Wherein, the step of adjusting the relative position of the firstsub-lens assembly with respect to the second sub-lens assembly comprisesthe following sub-steps:

moving the first sub-lens assembly with respect to the second sub-lensassembly within a first range in the adjustment plane, so as to increaseactual measured resolution of imaging of the optical system in areference field, obtained by using the photosensitive element, to acorresponding threshold;

and then adjusting an angle of an axis of the first sub-lens assemblywith respect to an axis of the second sub-lens assembly, so as toincrease actual measured resolution of imaging of the optical system ina test field, obtained by using the photosensitive element, to acorresponding threshold, and decrease an actual measured image planeinclination in the test field obtained by using the photosensitiveelement; and if the actual measured image plane inclination cannot reachthe second threshold, further performing a readjustment step until theactual measured image plane inclination is decreased to the secondthreshold.

Wherein, the readjustment step comprises:

moving the first sub-lens assembly with respect to the second sub-lensassembly within a second range in the adjustment plane, wherein thesecond range is smaller than the first range; and

adjusting an angle of a central axis of the first sub-lens assembly withrespect to a central axis of the second sub-lens assembly, so as todecrease the actual measured image plane inclination of imaging of theoptical system obtained by using the photosensitive element.

Wherein, in the connecting step, the first sub-lens assembly and thesecond sub-lens assembly are connected by a bonding or welding process.

Wherein, the welding process comprises laser welding or ultrasonicwelding.

Wherein, in the steps for preparing the first sub-lens assembly and thesecond sub-assembly, the second sub-lens assembly and the photosensitiveassembly are fixed by non-active alignment, to form the secondsub-assembly. The non-active alignment manner refers to a manner otherthan active alignment, for example, an alignment manner that does notrequire lighting up a module chip, such as mechanical alignment. Theactive alignment may be abbreviated as AA.

According to another aspect of the present invention, a camera module isfurther provided, comprising:

a first sub-lens assembly, comprising a first lens barrel and at leastone first lens; and

a second sub-assembly, comprising a second sub-lens assembly and aphotosensitive assembly fixed together, wherein the second sub-lensassembly comprises a second lens barrel and at least one second lens,and the photosensitive assembly comprises a photosensitive element,

wherein the first sub-lens assembly is arranged on an optical axis ofthe second sub-lens assembly to form an optical system capable ofimaging and comprising the at least one first lens and the at least onesecond lens;

and the first sub-lens assembly and the second sub-lens assembly arefixed together by a connecting medium, and the connecting medium isadapted to cause a central axis of the first sub-lens assembly to havean angle of inclination with respect to an axis of the second sub-lensassembly.

Wherein, the connecting medium is further adapted to cause the centralaxis of the first sub-lens assembly to be staggered with respect to thecentral axis of the second sub-lens assembly.

Wherein, the connecting medium is further adapted to cause the firstsub-lens assembly and the second sub-lens assembly to have a structuralclearance therebetween.

Wherein, the connecting medium is a bonding medium or a welding medium.

Wherein, the central axis of the first sub-lens assembly is staggeredwith respect to the central axis of the second sub-lens assembly by 0 to15 μm.

Wherein, the central axis of the first sub-lens assembly has an angle ofinclination of smaller than 0.5° with respect to the central axis of thesecond sub-lens assembly.

Wherein, the connecting medium is further adapted to cause a relativeposition of the first sub-lens assembly and the second sub-lens assemblyto remain unchanged, and the relative position cause actual measuredresolution of imaging of the optical system, obtained by using thephotosensitive element, to be increased to a first threshold, and causean actual measured image plane inclination of imaging of the opticalsystem, obtained by using the photosensitive element, to be decreased toa second threshold.

Wherein, the second sub-lens assembly further comprises a motor, theactual measured resolution is obtained when the motor is in on state,and the actual measured image plane inclination is obtained when themotor is in on state.

Wherein, outer side surfaces of the first sub-lens assembly and thesecond sub-lens assembly both have a contact surface facilitatingpick-up.

A clearance between 10 μm and 50 μm exists between the second sub-lensassembly and the photosensitive assembly.

Compared with the prior art, the present invention has at least one ofthe following technical effects.

In the present invention, the resolution of the camera module can beimproved.

In the present invention, the capability of process index (CPK) of massproduction of the camera module can be improved.

In the present invention, the requirements on the precision of variouselements of the optical imaging lens assembly and module and itsassembly precision can be lowered, and the overall costs of the opticalimaging lens assembly and module can be reduced.

In the present invention, the real-time adjustment of variousaberrations of the camera module during the assembly process can beimplemented, so as to reduce the failure rate and the production costs,and improve the imaging quality.

In the present invention, the relative position of the first sub-lensassembly and the second sub-assembly are adjusted over multiple degreesof freedom, so that aberration adjustment of the entire module can beimplemented at a time, thereby improving the imaging quality of theentire module.

In the present invention, the photosensitive assembly and the secondsub-lens assembly can be fixed by means of non-active alignment, therebyreducing the costs and improving the production efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are shown in the accompanying drawings. Theembodiments and accompanying drawings disclosed herein are provided forthe purpose of description, and should not be construed as limiting.

FIG. 1 is a flow chart of a method for assembling a camera moduleaccording to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a first sub-lens assembly, asecond sub-assembly and their initial positions according to anembodiment of the present invention.

FIG. 3 illustrates a relative position adjustment method according to anembodiment of the present invention.

FIG. 4 illustrates a rotational adjustment according to anotherembodiment of the present invention.

FIG. 5 illustrates a relative position adjustment method furtherallowing for adjustment in directions v and w according to still anotherembodiment of the present invention.

FIG. 6 illustrates MTF defocusing curves in an initial state accordingto an embodiment of the present invention.

FIG. 7 illustrates an example of MTF defocusing curves after adjustmentin step 310.

FIG. 8 illustrates the first sub-lens assembly, the second sub-assemblyand a positional relationship thereof after adjustment in step 310according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of an image plane inclination.

FIG. 10 is a schematic diagram of comparison of images at a centralposition, a periphery 1, and a periphery 1′.

FIG. 11 illustrates MTF defocusing curves after adjustment in step 400according to an embodiment of the present invention.

FIG. 12 illustrates a relative position of the first sub-lens assemblyand the second sub-lens assembly after adjustment in step 320 accordingto an embodiment of the present invention.

FIG. 13 illustrates a camera module formed after a connecting step isperformed according to an embodiment of the present invention.

FIG. 14 illustrates an example of targets setting according to anembodiment.

FIG. 15 illustrates a camera module according to an embodiment of thepresent invention.

FIG. 16 illustrates an assembled camera module having a motor accordingto an embodiment of the present invention, where the motor is in offstate.

FIG. 17 illustrates an assembled camera module having a motor accordingto an embodiment of the present invention, where the motor is in onstate.

DETAILED DESCRIPTION OF EMBODIMENTS

To facilitate the understanding of the present application, variousaspects of the present application will be described in further detailwith reference to the accompanying drawings. It should be understoodthat these detailed descriptions merely describe exemplaryimplementations of the present application, and are not intended tolimit the scope of the present application in any way. Throughout thisspecification, same reference numerals denote same parts. The term“and/or” includes any and all combinations of one or more of theassociated listed items.

It should be noted that in this specification, the terms such as “first”and “second” are merely used for distinguishing one feature fromanother, and are not intended to impose any limitation on the features.Therefore, a first subject discussed below may also be referred to asecond subject without departing from the teaching of the presentapplication.

In the accompanying drawings, for the convenience of illustration, thethicknesses, sizes, and shapes of objects are slightly exaggerated. Theaccompanying drawings are illustrative only and are not drawn strictlyto scale.

It will be further understood that the terms “comprises,” “comprising,”“having,”“includes,” and/or “including,” when used in thisspecification, specify the presence of stated features, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, steps, operations,elements, components, and/or groups thereof. In addition, expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of features, rather than individual elements in the list.Moreover, when the implementations of the present application aredescribed, the term “may” is used to indicate “one or moreimplementations of the present application”. Furthermore, the term“exemplary” is used to refer to illustrative description or descriptionby way of example.

As used herein, the terms “substantially”, “about”, and similar termsare used as terms of approximation and not as terms of degree, and areintended to account for the inherent deviations in measured orcalculated values that would be identified by those of ordinary skill inthe art.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by thoseof ordinary skill in the art to which the present application belongs.It will be further understood that terms, such as those defined incommonly used dictionaries, should be interpreted as having a meaningconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

It should be noted that the embodiments of the present application andthe features in the embodiments may be combined with each other on anon-conflict basis. The present application will be described below indetail with reference to the accompanying drawings and in combinationwith the embodiments.

FIG. 1 is a flow chart of a method for assembling a camera moduleaccording to an embodiment of the present invention. Referring to FIG.1, the method includes steps 100 to 400.

In step 100, a first sub-lens assembly and a second sub-assembly areprepared. FIG. 2 is a schematic diagram illustrating a first sub-lensassembly 1000, a second sub-assembly 6000 and their initial positionsaccording to an embodiment of the present invention. Referring to FIG.2, the first sub-lens assembly 1000 includes a first lens barrel 1100and at least one first lens 1200. In this embodiment, the number of thefirst lenses 1200 is two. However, it should be readily understood thatin other embodiments, the number of the first lenses 1200 may also haveother values, for example, one, three, or four.

The second sub-assembly 6000 includes a second sub-lens assembly 2000and a photosensitive assembly 3000 fixed together. The second sub-lensassembly 2000 includes a second lens barrel 2100 and at least one secondlens 2200. In this embodiment, the number of the second lenses 2200 isthree. However, it should be readily understood that in otherembodiments, the number of the second lenses 2200 may also have othervalues, for example, one, two, or four. In this embodiment, the secondlens barrel 2100 of the second sub-lens assembly 2000 includes an innerlens barrel 2110 and an outer lens barrel 2120 (where the outer lensbarrel 2120 may also be referred to as a lens base) nested together. Theinner lens barrel 2110 and the outer lens barrel 2120 are threadedlyconnected. It should be noted that the threaded connection is not theonly way for connecting the inner lens barrel 2110 and the outer lensbarrel 2120. Definitely, it should be readily understood that in otherembodiments, the second lens barrel 2100 may be an integral lens barrel.

Still referring to FIG. 2, in an embodiment, the photosensitive assembly3000 includes a circuit board 3100, a photosensitive element 3200mounted on the circuit board 3100, a tubular support 3400 fabricated onthe circuit board 3100 and surrounding the photosensitive element 3200,and a filter element 3300 mounted on the support 3400. The tubularsupport 3400 has an extension portion that extends inward (toward thephotosensitive element 3200) and that can serve as a lens bracket, andthe filter element 3300 is mounted on the extension portion. The tubularsupport 3400 further has an upper surface, and the photosensitiveassembly may be connected to other components (for example, the secondsub-lens assembly 2000) of the camera module via the upper surface.Definitely, it should be readily understood that in other embodiments,the photosensitive assembly 3000 may be of other structures. Forexample, the circuit board of the photosensitive assembly has a throughhole, and the photosensitive element is mounted in the through hole ofthe circuit board. For another example, a supporting portion is formedaround the photosensitive element by molding, and extends inward to comeinto contact with the photosensitive element (for example, thesupporting portion covers at least one part of a non-photosensitive areathat is located at an edge of the photosensitive element). For stillanother example, the photosensitive assembly may not include the filterelement.

Further, in an embodiment, the second sub-lens assembly 2000 and thephotosensitive assembly 3000 are fixed by means of non-active alignment,to form the second sub-assembly 6000. The active alignment may beabbreviated as AA. The non-active alignment manner refers to a mannerother than active alignment. For example, in an implementation, thesecond sub-lens assembly 2000 and the photosensitive assembly 3000 maybe fixed together by using a mechanical alignment manner, to form thesecond sub-assembly 6000.

In step 200, the first sub-lens assembly 1000 is arranged on an opticalaxis of the second sub-assembly 6000 to form an optical system capableof imaging and including the at least one first lens 1200 and the atleast one second lens 2200. In this step, arranging the first sub-lensassembly 1000 on the optical axis of the second sub-assembly 6000 meanspreliminarily aligning the two, to form an optical system capable ofimaging. That is to say, as long as the optical system including all thefirst lenses 1200 and all the second lenses 2200 is capable of imaging,it may be considered that the arrangement work in this step is complete.It should be noted that due to various fabrication tolerances of thesub-lens assembly and the photosensitive assembly during fabrication orother reasons, the central axes of the first lens barrel 1100 and thesecond lens barrel 2100 may not coincide with the optical axis after thearrangement is completed.

In step 300, a relative position of the first sub-lens assembly 1000with respect to the second sub-lens assembly 2000 is adjusted, so as tomaximize an actual measured resolution of imaging of the optical system(where when the actual measured resolution is increased to a presetthreshold, it may be considered that the actual measured resolution ismaximized), and minimize an actual measured image plane inclination ofimaging of the optical system that is obtained by using thephotosensitive element (where when the actual measured image planeinclination is decreased to a preset threshold, it may be consideredthat the actual measured image plane inclination is minimized). Theadjustment of the relative position of the first sub-lens assembly 1000and the second sub-lens assembly 2000 may be performed over multipledegrees of freedom.

FIG. 3 illustrates a relative position adjustment method according to anembodiment of the present invention. According to this adjustmentmethod, the first sub-lens assembly 1000 may be moved with respect tothe second sub-lens assembly 2000 in directions x, y, and z (that is,the adjustment of relative position in this embodiment can be performedin three degrees of freedom). The direction z is a direction along theoptical axis, and the directions x and y are directions perpendicular tothe optical axis. The directions x and y are both located in anadjustment plane P, and translation in the adjustment plane P can bedecomposed into two components in the directions x and y.

FIG. 4 illustrates a rotational adjustment according to anotherembodiment of the present invention. In this embodiment, the adjustmentof relative position can be not only performed in the three degrees offreedom shown in FIG. 3, but also performed in a rotational degree offreedom, that is, adjustment in a direction r. In this embodiment, theadjustment in the direction r is rotation in the adjustment plane P,that is, rotation about an axis perpendicular to the adjustment plane P.

Further, FIG. 5 illustrates a relative position adjustment methodfurther allowing for adjustment in directions v and w according to stillanother embodiment of the present invention. In FIG. 5, the direction vrepresents an angle of rotation in the xoz plane, the direction wrepresents an angle of rotation in the yoz plane, and the angles ofrotation in the direction v and the direction w may form a vector angle,which represents the overall inclination state. That is to say, theinclination posture of the first sub-lens assembly with respect to thesecond sub-lens assembly (that is, the inclination of the optical axisof the first sub-lens assembly with respect to the optical axis of thesecond sub-lens assembly) may be adjusted by adjustment in the directionv and the direction w.

Adjustment over the above-mentioned six degrees of freedom in thedirections x, y, z, r, v, and w may all affect the imaging quality ofthe optical system (for example, the value of the resolution). In otherembodiments of the present invention, the method for adjusting therelative position may be performed in any one of, or any two or more ofthe above-mentioned six degrees of freedom.

Further, in an embodiment, a method for obtaining the actual measuredresolution of imaging of the optical system includes steps 301 and 302.

In step 301, a plurality of targets corresponding to a reference fieldand/or a test field is set. For example, a center field may be selectedas the reference field, and one or more fields corresponding to a regionof interest may be selected as the test field (for example, 80% field).

In step 302, a resolution defocusing curve corresponding to each targetis acquired based an image output by the photosensitive assembly.According to the resolution defocusing curve, actual measured resolutionof the corresponding field can be obtained.

In this embodiment, the resolution may be represented by a modulationtransfer function (MTF). A larger MTF value indicates higher resolution.In this way, according to the MTF defocusing curve acquired based on theimage output by the photosensitive assembly, the resolution of imagingof the optical system can be obtained in real time. According to thevariation of the MTF defocusing curve, it can be determined whether amaximum resolution has been reached currently. FIG. 6 illustrates MTFdefocusing curves in an initial state according to an embodiment of thepresent invention, including an MTF defocusing curve of the center fieldand MTF defocusing curves of imaging of two targets located in the testfield in a sagittal direction and a meridian direction.

On the other hand, an image plane inclination often occurs duringimaging of the optical system. FIG. 9 is a schematic diagram of an imageplane inclination. It can be seen that in FIG. 9, an object planeperpendicular to the optical axis forms an inclined image plane afterlens imaging. Incident light of the center field is focused at a centralfocus after passing through a lens. Incident light of an off-axis field1 is focused at a peripheral focus 1′ after passing through the lens,where there is an axial deviation D2 between the peripheral focus 1′ andthe central focus. Incident light of an off-axis field 1′ is focused ata peripheral focus 1 after passing through the lens, where there is anaxial deviation D1 between the peripheral focus 1 and the central focus.As a result, when the receiving surface of the photosensitive element isdisposed perpendicularly to the optical axis, clear imaging cannot beachieved at the periphery 1 and the periphery 1′. FIG. 10 is a schematicdiagram of comparison of images at the central position, the periphery1, and the periphery 1′. It can be seen that images at the periphery 1and the periphery 1′ are obviously more blurred than the image at thecentral position. In the present invention, the angle of inclinationbetween the first sub-lens assembly and the second sub-lens assembly maybe adjusted to compensate for the above-mentioned image planeinclination.

In an embodiment, a method for acquiring the actual measured image planeinclination includes steps 303 and 304.

In step 303, for any test field (for example, 80% field), a plurality oftargets corresponding to different test positions in the test field isset. FIG. 14 illustrates an example of a target setting method accordingto an embodiment.

As shown in FIG. 14, the test field is 80% field, and four targets arerespectively disposed at four corners of a chart.

In step 304, each resolution defocusing curve corresponding to differentpositions in a same field is acquired based on an image output by thephotosensitive assembly. When the resolution defocusing curves convergeon the abscissa axis (the coordinate axis representing a defocusingamount along the optical axis direction), it indicates that the imageplane inclination corresponding to the test field has been compensatedfor. That is, the minimization of the actual measured image planeinclination has been achieved in the test field. In an embodiment, if aposition offset in the optical axis direction between peaks ofresolution defocusing curves corresponding to different test positionsin a test field are decreased to a preset threshold, it indicates thatthe image plane inclination corresponding to the test field has beencompensated for.

Further, in an embodiment, step 300 includes steps 310 and 320.

In step 310, the actual measured resolution of imaging of the opticalsystem is increased to a corresponding threshold by moving the firstsub-lens assembly 1000 with respect to the second sub-lens assembly 2000in an adjustment plane P. The adjustment over six degrees of freedom inthe directions x, y, z, r, v, and w has been described above.Translation in the directions x and y and rotation in the direction rmay be considered to be movement in the adjustment plane P in this step.In this step, a plurality of targets corresponding to the referencefield and the test field is set, and then a resolution defocusing curvecorresponding to each target is acquired based on an image output by thephotosensitive assembly. The first sub-lens assembly 1000 is moved withrespect to the second sub-lens assembly 2000 in the directions x, y, andr, so that a peak of a resolution defocusing curve corresponding toimaging of a target in the reference field is increased to acorresponding threshold. The center field may be used as the referencefield. However, it should be noted that the reference field is notlimited to the center field. In some embodiments, other fields may alsobe selected as the reference field. In this step, increasing the actualmeasured resolution to a corresponding threshold is: increasing a peakof a resolution defocusing curve corresponding to imaging of a target inthe reference field to a corresponding threshold.

FIG. 7 illustrates an example of MTF defocusing curves after adjustmentin step 310. It can be seen that after the adjustment, MTF values ofimaging of the two targets in the sagittal direction and the meridiandirection both increase obviously. FIG. 8 illustrates the first sub-lensassembly 1000, the second sub-assembly 6000 and a positionalrelationship thereof after adjustment in step 310 according to anembodiment of the present invention. It can be seen that the centralaxis of the first sub-lens assembly 1000 is offset with respect to thecentral axis of the second sub-lens assembly 2000 in the direction x byΔx. It should be noted that FIG. 8 is merely exemplary. Although nooffset in the direction y is shown in FIG. 8, it should be readilyunderstood by those skilled in the art that the central axis of thefirst sub-lens assembly 1000 may also be offset with respect to thecentral axis of the second sub-lens assembly 2000 in the direction y byΔy.

In step 320, the axis of the first sub-lens assembly 1000 is tilted withrespect to the axis of the second sub-lens assembly 2000, so as toincrease the actual measured resolution of imaging of the optical systemin the test field to a corresponding threshold, and decrease the actualmeasured image plane inclination of imaging of the optical system in thetest field to a corresponding threshold. Rotation in the directions vand w corresponds to the tilting adjustment in this step. In this step,increasing the actual measured resolution to a corresponding thresholdincludes: increasing the smallest one of peaks of resolution defocusingcurves corresponding to imaging of a plurality of targets of differenttest positions in the test field to a corresponding threshold. In otherembodiments, increasing the actual measured resolution to acorresponding threshold may further include: increasing uniformity ofthe peaks of the resolution defocusing curves corresponding to imagingof the plurality of targets of different test positions in the testfield to a corresponding threshold. Increasing the uniformity of thepeaks includes: decreasing a variance of the peaks of the resolutiondefocusing curves corresponding to imaging of the plurality of targetsin the test field to a corresponding threshold. Decreasing the actualmeasured image plane inclination of imaging of the optical system in thetest field to a corresponding threshold includes: making a positionoffset of the peak values of the resolution defocusing curvescorresponding to different test positions in the test field along theoptical axis direction reduce to the corresponding threshold.

FIG. 11 illustrates MTF defocusing curves after adjustment instep 320according to an embodiment of the present invention. FIG. 12 illustratesa relative position of the first sub-lens assembly and the secondsub-lens assembly after adjustment instep 320 according to an embodimentof the present invention. It can be seen in FIG. 12 that, the centralaxis of the first sub-lens assembly is offset with respect to thecentral axis of the second sub-lens assembly in the direction x by Δx,and the central axis of the first sub-lens assembly 1000 is alsoinclined with respect to the central axis of the second sub-lensassembly 2000 by Δv2. Although no inclination in the direction w isshown in FIG. 12, it should be readily understood by those skilled inthe art that the axis of the photosensitive assembly 3000 may also havean angle of inclination with respect to the central axis of the secondsub-lens assembly 2000 in the direction w.

In step 400, the first sub-lens assembly 1000 and the second sub-lensassembly 2000 are connected, so that the relative position of the firstsub-lens assembly 1000 and the second sub-lens assembly 2000 remainunchanged. FIG. 13 illustrates a camera module formed after a connectingstep is performed according to an embodiment of the present invention.

The process for connecting the first sub-lens assembly and the secondsub-lens assembly may be selected as required. For example, in anembodiment, the first sub-lens assembly and the second sub-lens assemblyare connected by a bonding process. As shown in FIG. 13, in thisembodiment, the first sub-lens assembly 1000 and the second sub-lensassembly 2000 are bonded by using an adhesive material 4000. In anotherembodiment, the first sub-lens assembly and the second sub-lens assemblymay be connected by a laser welding process. In still anotherembodiment, the first sub-lens assembly and the second sub-lens assemblymay be connected by an ultrasonic welding process. In addition to theabove-mentioned processes, other welding processes may also be used. Itshould be noted that in the present invention, the term “connection” isnot limited to direct connection. For example, in an embodiment, thefirst sub-lens assembly and the second sub-lens assembly may beconnected via an intermediate member (which maybe rigid). Suchconnection via an intermediate member falls within the meaning of theterm “connection” as long as the relative position of (includingrelative distance and posture) of the first sub-lens assembly and thesecond sub-lens assembly (or the photosensitive assembly and the secondsub-lens assembly) remain unchanged.

The method for assembling a camera module according to theabove-mentioned embodiment can improve the resolution of the cameramodule and the capability of process index (CPK) of mass production ofthe camera module; can lower the requirements on the precision ofvarious elements of the optical imaging lens assembly and module and itsassembly precision, and reduce the overall costs of the optical imaginglens assembly and module. The method can implement a real-timeadjustment of various aberrations of the camera module during theassembly process to reduce the fluctuation of the imaging quality,thereby reducing the failure rate and the production costs, andimproving the imaging quality.

Further, in an embodiment, step 300 may further include: matching anactual measured image plane of imaging of the optical system with atarget surface by moving the first sub-lens assembly with respect to thesecond sub-lens assembly in the optical axis direction. The adjustmentover six degrees of freedom in the directions x, y, z, r, v, and w hasbeen described above. Movement in the direction z may be considered tobe movement in the optical axis direction in this step.

After the optical lens assembly is assembled, an expected imagingsurface will be obtained. Herein, the expected imaging surface isreferred to as the target surface. In some cases, the target surface isa plane. For example, to achieve optimal imaging quality, if thephotosensitive surface of the photosensitive element of the cameramodule corresponding to the optical lens assembly is a plane, theexpected imaging surface of the optical lens assembly is also a plane.That is to say, the target surface is a plane. In some other cases, thetarget surface may be a convex or concave curved surface, or acorrugated curved surface. For example, to achieve optimal imagingquality, if the photosensitive surface of the photosensitive element ofthe camera module corresponding to the optical lens assembly is a convexor concave curved surface, the target surface should also be a convex orconcave curved surface; if the photosensitive surface of thephotosensitive element of the camera module corresponding to the opticallens assembly is a corrugated curved surface, the target surface shouldalso be a corrugated curved surface.

In an embodiment, it is identified according to an image output by thephotosensitive element whether the actual measured image plane matchesthe target surface. In the step of matching the actual measured imageplane with the target surface, matching the actual measured image planewith the target surface includes: obtaining an actual measured fieldcurvature of the module according to the image output by thephotosensitive element, and causing the actual measured field curvatureof the module to fall within a range of +/−5 μm. This embodiment canfurther improve the imaging quality of the camera module.

Further, in an embodiment, in step 320, targets are set in pair for theselected test field. For example, a pair of first targets respectivelylocated at two ends of the central position are set in a firstdirection, and a pair of second targets respectively located at two endsof the central position are set in a second direction. As shown in FIG.14, the test field is 80% field, and the four targets are respectivelydisposed at four corners of a chart. The lower left target and the upperright target may be used as the pair of first targets in the firstdirection, and the upper left target and the lower right target may beused as the pair of second targets in the second direction. Aninclination component of the actual measured image plane of imaging ofthe optical system in the first direction can be identified according toan offset vector of a resolution defocusing curve of the pair of firsttargets in the abscissa axis direction (that is, the optical axisdirection), and an inclination component of the actual measured imageplane of imaging of the optical system in the second direction can beidentified according to an offset vector of a resolution defocusingcurve of the pair of second targets in the abscissa axis direction.Then, the posture of the first sub-lens assembly with respect to thesecond sub-lens assembly is adjusted to change the angle of the axis ofthe first sub-lens assembly with respect to the axis of the secondsub-lens assembly, so as to compensate for the inclination component inthe first direction and the inclination component in the seconddirection.

Further, in an embodiment, in step 310, the first sub-lens assembly ismoved with respect to the second sub-lens assembly within a first rangein the adjustment plane.

In step 320, if the actual measured image plane inclination cannot bedecreased to fall within a preset range, a readjustment step 330 isfurther performed until the actual measured image plane inclination isdecreased to fall within the preset range.

The readjustment step 330 includes step 331 and 332.

In step 331, the first sub-lens assembly is moved with respect to thesecond sub-lens assembly within a second range in the adjustment plane.The second range is smaller than the first range. That is to say,compared with step 310, in step 331, the relative position of the firstsub-lens assembly and the second sub-lens assembly are adjusted within asmall range in the adjustment plane. On one hand, because the adjustmentrange is small, the actual measured resolution achieved after theadjustment in step 310 can basically be maintained. On the other hand,the image plane inclination can be reduced, making it easier tocompensate for the image plane inclination in step 332.

In step 332, the angle of the central axis of the first sub-lensassembly with respect to the central axis of the second sub-lensassembly is adjusted, so that an actual measured image plane inclinationof imaging of the optical system, obtained by using the photosensitiveelement, is decreased to a corresponding threshold. If the actualmeasured image plane inclination cannot be decreased to fall within thepreset range, the above-mentioned steps 331 and 332 are repeated untilthe actual measured image plane inclination is decreased to fall withinthe preset range.

According to an embodiment of the present invention, a camera moduleobtained by the above-mentioned method for assembling a camera module isfurther provided. FIG. 15 illustrates the camera module in thisembodiment. Referring to FIG. 15, the camera module includes a firstsub-lens assembly 1000 and a second sub-assembly 6000. The firstsub-lens assembly 1000 includes a first lens barrel 1100 and at leastone first lens 1200. The second sub-assembly 6000 includes a secondsub-lens assembly 2000 and a photosensitive assembly 3000 fixedtogether. The second sub-lens assembly 2000 includes a second lensbarrel 2100 and at least one second lens 2200. The photosensitiveassembly 3000 includes a photosensitive element 3300.

The first sub-lens assembly 1000 is arranged on an optical axis of thesecond sub-lens assembly 2000 to form an optical system capable ofimaging and including the at least one first lens 1200 and the at leastone second lens 2200.

The first sub-lens assembly 1000 and the second sub-lens assembly 2000are fixed together by a connecting medium 4000.

The connecting medium 4000 is adapted to cause a central axis of thefirst sub-lens assembly 1000 to have an angle of inclination of smallerthan 0.5° with respect to a central axis of the second sub-lens assembly2000. The connecting medium 4000 is further adapted to cause therelative position of the first sub-lens assembly 1000 and the secondsub-lens assembly 2000 to remain unchanged. The relative position causeactual measured resolution of imaging of the optical system, obtained byusing the photosensitive element 3300, to be increased to a firstthreshold, and cause an actual measured image plane inclination ofimaging of the optical system, obtained by using the photosensitiveelement 3300, to be decreased to a second threshold.

In an embodiment, the connecting medium may be an adhesive material or abonding pad (for example, a metal sheet). The second connecting mediummay be an adhesive material or a bonding pad (for example, a metalsheet). The connecting medium by which the first sub-lens assembly andthe second sub-lens assembly are connected and fixed together is neitherpart of the first sub-lens assembly, nor part of the second sub-lensassembly.

In an embodiment, the connecting medium is further adapted to cause thecentral axis of the first sub-lens assembly to be staggered with respectto the central axis of the second sub-lens assembly by 0 to 15 μm.

In an embodiment, the connecting medium is further adapted to cause thefirst sub-lens assembly and the second sub-lens assembly to have astructural clearance therebetween. The first sub-lens assembly 1000 andthe second sub-lens assembly 2000 both have an optical surface and astructural surface. In the lens assembly, the optical surface is asurface, through which effective light passes, on a lens. Other surfaceson the lens than the optical surface are the structural surfaces.Surfaces located on the lens barrel are all structural surfaces. Thestructural clearance is a clearance between structural surfaces.

Further, in an embodiment, the second sub-lens assembly 2000 and thephotosensitive assembly 3000 are assembled together by means ofmechanical alignment, to form the second sub-assembly 6000. A clearance5000 between 10 μm and 50 μm adapted for mechanical alignment existsbetween the second sub-lens assembly 2000 and the photosensitiveassembly 3000.

The central axis of the first sub-lens assembly and the central axis ofthe second sub-lens assembly are mentioned multiple times herein.Referring to FIG. 16, for the convenience of measurement, the centralaxis of the first sub-lens assembly 1000 may be construed as a centralaxis of an optical surface 1201, which is closest to the second sub-lensassembly 2000, in the first sub-lens assembly 1000; or may be construedas a central axis defined by a structural surface 1202 of the first lens1200 that is closest to the second sub-lens assembly 2000. When thefirst lens 1200 and the first lens barrel 1100 of the first sub-lensassembly 1000 are tightly assembled, the central axis of the firstsub-lens assembly 1000 may also be construed as a central axis definedby an inner side surface of the first lens barrel.

Similarly, for the convenience of measurement, the central axis of thesecond sub-lens assembly 2000 may be construed as a central axis of anoptical surface 2201, which is closest to the first sub-lens assembly1000, in the second sub-lens assembly 2000; or may be construed as acentral axis defined by a structural surface 2202 of the second lens2200 that is closest to the first sub-lens assembly 1000. When thesecond lens 2200 and the second lens barrel 2100 of the second sub-lensassembly 2000 are tightly assembled, the central axis of the secondsub-lens assembly 2000 may also be construed as a central axis definedby an inner side surface of the second lens barrel.

The present invention is particularly suitable for a miniature cameramodule that is applied to a smart terminal and that includes a lensassembly having a diameter of less than 10 mm. In an embodiment, outerside surfaces of the first sub-lens assembly and the second sub-lensassembly both provide a sufficient contact surface, so that a mechanicalarm (or other pick-up apparatus) can pick up (for example, clamp orsuck) the first sub-lens assembly and the second sub-lens assembly viathe contact surface, thereby implementing the precise adjustment of therelative position of the first sub-lens assembly and the second sub-lensassembly. Such precise adjustment may be adjustment in six degrees offreedom. The adjustment step may reach the micron order or a moreprecise level.

Further, in an embodiment, the second sub-lens assembly 2000 may furtherinclude a motor, so as to achieve autofocusing of a camera module of amobile phone. FIG. 16 illustrates an assembled camera module having amotor according to an embodiment of the present invention, where themotor is in off state. FIG. 17 illustrates an assembled camera modulehaving a motor according to an embodiment of the present invention,where the motor is in on state. In this embodiment, the motor includes amotor base 2310 and a motor support 2320 mounted on the motor base 2310.The motor support 2320 surrounds the second lens barrel 2100, and adriving structure (not shown) of the motor is mounted on the motorsupport 2320. The motor support 2320 is connected to the second lensbarrel 2100 by a reed 2330. When the driving structure is electrified,the second lens barrel moves along the optical axis, and the reed 2330deforms (as shown in FIG. 17). In step 310 and step 320, the motor, thesecond lens barrel 2100, and the second lens 2200 mounted in the secondlens barrel 2100 are moved and adjusted as the whole second sub-lensassembly 2000. In step 500, the motor base 2310 and the photosensitiveassembly 3000 are connected so as to achieve the connection between thesecond sub-lens assembly 2000 and the photosensitive assembly 3000.Further, in step 310, when the relative position of the first sub-lensassembly and the second sub-lens assembly are adjusted, the motor ismaintained in on state (for example, the motor being electrified may beconsidered to indicate that the motor is started). In this way, theactual measured resolution acquired is actual measured resolutionobtained when the motor is in on state. In step 320, when the angle ofinclination of the photosensitive assembly with respect to the centralaxis of the second sub-lens assembly is adjusted, the motor is alsomaintained in on state. In this way, the actual measured image planeinclination acquired is an actual measured image plane inclinationobtained when the motor is in on state. After the motor is started, thereed deforms correspondingly. However, compared with the case where themotor is in off state, the deformation of the reed due to starting ofthe motor may lead to an additional inclination of the central axis ofthe second lens barrel with respect to the central axis of the firstsub-lens assembly (referring to the angle of inclination Δv4 in FIG.17). In the solution of this embodiment, the additional inclination ofthe second lens barrel caused by starting of the motor can becompensated for during the adjustment in step 310 and step 320, therebyfurther improving the imaging quality of the autofocus camera module.

The foregoing is only a description of the preferred implementations ofthe present application and the applied technical principles. It shouldbe appreciated by those skilled in the art that the inventive scope ofthe present application is not limited to the technical solutions formedby the particular combinations of the above technical features. Theinventive scope should also cover other technical solutions formed byany combinations of the above technical features or equivalent featuresthereof without departing from the concept of the invention, such as,technical solutions formed by replacing the features as disclosed in thepresent application with (but not limited to), technical features withsimilar functions.

1. A method for assembling a camera module, the method comprising:preparing a first sub-lens assembly and a second sub-assembly, whereinthe first sub-lens assembly comprises a first lens barrel and at leastone first lens, the second sub-assembly comprises a second sub-lensassembly and a photosensitive assembly fixed together, the secondsub-lens assembly comprises a second lens barrel and at least one secondlens, and the photosensitive assembly comprises a photosensitiveelement; arranging the first sub-lens assembly on an optical axis of thesecond sub-lens assembly to form an optical system capable of imagingand comprising the at least one first lens and the at least one secondlens; adjusting a relative position of the first sub-lens assembly withrespect to the second sub-lens assembly, so as to increase an actualmeasured resolution of imaging of the optical system, obtained by usingthe photosensitive element, to a first threshold, and decrease an actualmeasured image plane inclination obtained by using the photosensitiveelement to a second threshold; and connecting the first sub-lensassembly and the second sub-lens assembly, so that the relative positionof the first sub-lens assembly and the second sub-lens assembly remainunchanged.
 2. The method for assembling a camera module according toclaim 1, wherein in the step of adjusting the relative position of thefirst sub-lens assembly with respect to the second sub-lens assembly,the adjusting the relative position comprises: increasing the actualmeasured resolution of imaging of the optical system by moving the firstsub-lens assembly with respect to the second sub-lens assembly in anadjustment plane.
 3. The method for assembling a camera module accordingto claim 2, wherein in the step of adjusting the relative position ofthe first sub-lens assembly with respect to the second sub-lensassembly, the movement in the adjustment plane comprises translationand/or rotation in the adjustment plane.
 4. The method for assembling acamera module according to claim 1, wherein in the step of adjusting therelative position of the first sub-lens assembly with respect to thesecond sub-lens assembly, the adjusting the relative position comprises:adjusting an angle of an axis of the first sub-lens assembly withrespect to an axis of the second sub-lens assembly.
 5. The method forassembling a camera module according to claim 1, wherein the step ofadjusting the relative position of the first sub-lens assembly withrespect to the second sub-lens assembly comprises the followingsub-steps: moving the first sub-lens assembly with respect to the secondsub-lens assembly in an adjustment plane, so as to increase actualmeasured resolution of imaging of the optical system in a referencefield, obtained by using the photosensitive element, to a correspondingthreshold; and adjusting an angle of an axis of the first sub-lensassembly with respect to an axis of the second sub-lens assembly, so asto increase actual measured resolution of imaging of the optical systemin a test field, obtained by using the photosensitive element, to acorresponding threshold, and decrease an actual measured image planeinclination in the test field, obtained by using the photosensitiveelement, to the second threshold.
 6. The method for assembling a cameramodule according to claim 5, wherein the step of adjusting the relativeposition of the first sub-lens assembly with respect to the secondsub-lens assembly further comprises: moving the first sub-lens assemblywith respect to the second sub-lens assembly in a direction z, so thatan actual measured image plane of imaging of the optical system,obtained by using the photosensitive element, matches a target surface,wherein the direction z is a direction along the optical axis. 7.(canceled)
 8. The method for assembling a camera module according toclaim 5, wherein obtaining the actual measured image plane inclinationcomprises: For the test field, setting a plurality of targetscorresponding to different test positions in the test field; andacquiring a resolution defocusing curve corresponding to each testposition based on an image output by the photosensitive assembly.
 9. Themethod for assembling a camera module according to claim 8, wherein thedecreasing the actual measured image plane inclination to the secondthreshold is: making a position offset of the peak values of theresolution defocusing curves corresponding to different test positionsin the test field along the optical axis direction reduce to the secondthreshold.
 10. The method for assembling a camera module according toclaim 9, wherein the decreasing the actual measured image planeinclination to the second threshold is: making a position offset of thepeak values of the resolution defocusing curves corresponding todifferent test positions in the test field along the optical axisdirection reduce to a range of +/−5 μm.
 11. The method for assembling acamera module according to claim 5, wherein obtaining the actualmeasured resolution of imaging of the optical system comprises: settinga plurality of targets corresponding to different test positions in thereference field and the test field; and acquiring a resolutiondefocusing curve corresponding to each test position based on an imageoutput by the photosensitive assembly.
 12. The method for assembling acamera module according to claim 11, wherein in the sub-step of movingthe first sub-lens assembly with respect to the second sub-lens assemblyin an adjustment plane, the increasing the actual measured image planeinclination to a corresponding threshold is: increasing peaks ofresolution defocusing curves corresponding to different test positionsin the reference field to a corresponding threshold.
 13. The method forassembling a camera module according to claim 11, wherein in thesub-step of adjusting an angle of an axis of the first sub-lens assemblywith respect to an axis of the second sub-lens assembly, the increasingthe actual measured resolution to a corresponding threshold comprises:increasing a smallest one of peaks of a plurality of resolutiondefocusing curves corresponding to different test positions in the testfield to a corresponding threshold.
 14. The method for assembling acamera module according to claim 1, wherein the step of adjusting therelative position of the first sub-lens assembly with respect to thesecond sub-lens assembly comprises the following sub-steps: moving thefirst sub-lens assembly with respect to the second sub-lens assemblywithin a first range in the adjustment plane, so as to increase actualmeasured resolution of imaging of the optical system in a referencefield, obtained by using the photosensitive element, to a correspondingthreshold; and then adjusting an angle of an axis of the first sub-lensassembly with respect to an axis of the second sub-lens assembly, so asto increase actual measured resolution of imaging of the optical systemin a test field, obtained by using the photosensitive element, to acorresponding threshold, and decrease an actual measured image planeinclination in the test field obtained by using the photosensitiveelement; and if the actual measured image plane inclination cannot reachthe second threshold, further performing a readjustment step until theactual measured image plane inclination is decreased to the secondthreshold, wherein the readjustment step comprises: moving the firstsub-lens assembly with respect to the second sub-lens assembly within asecond range in the adjustment plane, wherein the second range issmaller than the first range; and adjusting an angle of a central axisof the first sub-lens assembly with respect to a central axis of thesecond sub-lens assembly, so as to decrease the actual measured imageplane inclination of imaging of the optical system obtained by using thephotosensitive element.
 15. (canceled)
 16. (canceled)
 17. (canceled) 18.A camera module, comprising: a first sub-lens assembly, comprising afirst lens barrel and at least one first lens; and a secondsub-assembly, comprising a second sub-lens assembly and a photosensitiveassembly fixed together, wherein the second sub-lens assembly comprisesa second lens barrel and at least one second lens, and thephotosensitive assembly comprises a photosensitive element, wherein thefirst sub-lens assembly is arranged on an optical axis of the secondsub-lens assembly to form an optical system capable of imaging andcomprising the at least one first lens and the at least one second lens;and the first sub-lens assembly and the second sub-lens assembly arefixed together by a connecting medium, and the connecting medium isadapted to cause a central axis of the first sub-lens assembly to havean angle of inclination with respect to an axis of the second sub-lensassembly.
 19. The camera module according to claim 18, wherein theconnecting medium is further adapted to cause the central axis of thefirst sub-lens assembly to be staggered with respect to the central axisof the second sub-lens assembly.
 20. The camera module according toclaim 18, wherein the connecting medium is further adapted to cause thefirst sub-lens assembly and the second sub-lens assembly to have astructural clearance therebetween.
 21. (canceled)
 22. (canceled)
 23. Thecamera module according to claim 18, wherein the central axis of thefirst sub-lens assembly has an angle of inclination of smaller than 0.5°with respect to the central axis of the second sub-lens assembly. 24.The camera module according to claim 18, wherein the connecting mediumis further adapted to cause a relative position of the first sub-lensassembly and the second sub-lens assembly to remain unchanged, and therelative position cause actual measured resolution of imaging of theoptical system, obtained by using the photosensitive element, to beincreased to a first threshold, and cause an actual measured image planeinclination of imaging of the optical system, obtained by using thephotosensitive element, to be decreased to a second threshold.
 25. Thecamera module according to claim 24, wherein the second sub-lensassembly further comprises a motor, the actual measured resolution isobtained when the motor is in on state, and the actual measured imageplane inclination is obtained when the motor is in on state. 26.(canceled)
 27. The camera module according to claim 18, wherein aclearance between 10 μm and 50 μm exists between the second sub-lensassembly and the photosensitive assembly.